Postal voting is voting in an election where ballot papers are distributed to electors (and typically returned) by post, in contrast to electors voting in person at a polling station or electronically via an electronic voting system.

In an election, postal votes may be available on demand or limited to individuals meeting certain criteria, such as a proven inability to travel to a designated polling place. Most electors are required to apply for a postal vote, although some may receive one by default. In some elections postal voting is the only voting method allowed and is referred to as all-postal voting. With the exception of those elections, postal votes constitute a form of early voting and may be considered an absentee ballot.

Typically, postal votes must be mailed back before the scheduled election day. However, in some jurisdictions return methods may allow for dropping off the ballot in person via secure drop boxes or at voting centers. Postal votes may be processed by hand or scanned and counted electronically. The history of postal voting dates back to the 19th century, and modern-day procedures and availability vary by jurisdiction. Research, focused on the United States and using data from states where postal voting is widely available—California, Oregon and Washington—shows that the availability of postal voting tends to increase voter turnout.

Electoral laws typically stipulate a series of checks to protect against voter fraud and allow for the integrity and secrecy of the submitted ballot to be maintained. Known instances of fraud are very rare. Coordinated, large-scale fraud by postal voting is likely hard to pull off undetected because the large number of interested parties (such as officials, political operators, and journalists) as well as a large number of scholars and analysts who are capable of detecting statistical outliers in vote totals signifying large-scale fraud. Officials can confirm instances of fraud by checking signatures and conducting basic detective work.

All-postal voting is a form of postal voting in which all electors receive their ballot papers through the post, not just those who requested an absentee ballot. Depending on the country, electors may have to return their ballot papers by post or they may be allowed to deliver them by hand to specified drop-off locations. All-postal voting is used in several states in the United States and in Switzerland, and was used in 2016 in the Australian Marriage Law Postal Survey as well as in four regions of the United Kingdom in the 2004 European Parliament election.

There is some evidence that all-postal voting leads to higher turnout than in-person voting or mail-in voting that requires voters to first request a ballot (rather than receive it automatically).

At the 2016 Australian federal election, there were 1.2 million postal votes cast, amounting to 8.5 percent of total votes.

Postal voting in Australia was introduced for federal elections in 1902, and first used at the 1903 election. It was abolished by the Fisher government in 1910, following claims that it was open to abuse and biased towards rural voters. The Cook government's bill to restore postal voting was one of the "triggers" for the double dissolution prior to the 1914 election. Postal voting was eventually restored by the Hughes government in 1918 and has not been challenged since, although the provisions and requirements have been amended on a number of occasions.